1. Field of the Invention
This invention relates to processes for preparing lactones and, more particularly, to processes for preparing 2-butenolide (also known as gamma-crotonolactone) by the catalyzed vapor phase reaction of furan and oxygen.
2. Description of the Prior Art
2-Butenolide, an unsaturated lactone, readily undergoes catalytic hydrogenation in a known and conventional matter to provide the saturated lactone, gamma-butyrolactone, according to the equation: ##STR1##
Assuming the availability of a relatively low cost source of 2-butenolide, the foregoing synthesis of gamma-butyrolactone would be a commercially attractive route to the production of the latter compound, an important intermediate for the manufacture of butyric and succinic acids, 1,4-butanediol and other industrially important products.
While processes for the preparation of unsaturated lactones are known (e.g., the process of U.S. Pat. No. 3,458,532 to Hayden which provides unsaturated lactones by the carbonylation of ethylene or propylene in the presence of a palladium salt as catalyst and the process of U.S. Pat. No. 4,119,642 to Larock which provides beta-halobutenolides by the carbonylation of vinylmercurials in the presence of a basic inorganic salt), a convenient one-step synthesis of 2-butenolide employing relatively abundant, low cost and readily available raw materials has heretofore not been made available.